Re-analysis opens a big can of #WormWars

A spirited debated ensued in the wake of the publication of studies trying to replicate a famous deworming evaluation. Buckle up kids, this is going to be a wonky ride!


  1. Note: I will do my best to keep this as up to date as possible, but there are a lot of tweets and the conversation is starting to go in circles.
  2. Once upon a time, a team of researchers tested the impact of worms on health and education in western Kenya. They found that school-wide deworming programs can reduce the incidence of children getting worms and keep them in the classroom. With the low price of the deworming drugs and the high effect, it was hearalded as cost-effective way to improve health and education.
  3. Fast forward roughly a decade and governments from Kenya to India are deploying mass deworming campaigns for children. But then came questions about the original research. The Cochrane Collaboration published a systematic review of deworming in 2012. They looked at all the research that followed the Kenya study and determined that deworming is not all that its cracked up to be.
  4. "For routine deworming of school children in endemic areas, there is quite substantial evidence that deworming programmes do not show benefit in terms of average nutritional status, haemoglobin, cognition, school performance, or death," concluded the Cochrane authors.
  5. The authors of the original study offered a response saying, "In sum, a re-analysis of Miguel and Kremer3 confirms its main conclusions regarding deworming treatment externalities and school participation gains, and these school participation gains are robust across a wide range of adequately powered analysis methods. "
  6. Responses came quickly disputing the claims made in the analysis.
  7. The debate subsided for two years, until a re-analysis of the western Kenya study appeared.
  8. The World Bank's Berk Ozler took a look at the reanalysis and concluded that it does not really change the overall findings in support of deworming programs. He concluded: "Based on what I have seen in the reanalysis study by DAHH and the response by HKM, my view of the original study is more or less unchanged. In fact, if anything, I find the findings of the original study more robust than I did before."
  9. The final versions of the re-analysis were published in the International Journal of Epidemology yesterday.
  10. The researchers from the original Kenya study published a written response to the re-analysis disagreeing with many of the findings.
  11. And the re-analysis authors responded to the original authors.
  12. To keep things simple, here is a single page with all the above papers, responses and commentaries published by IJE on this.